An imaging system for imaging a region of interest comprising a moving object is, for example, a computed tomography system for imaging a heart of a patient. Such a computed tomography system is generally be referred to as cardiac CT system. The cardiac CT system comprises an electrocardiograph for determining phase positions of the heart, wherein for a reconstruction of a region of interest of the heart only detection values are used, which have been acquired at certain phase positions of the heart, at which the heart is in a relative rest condition. Thus, only a part of the detection values is used for reconstructing a region of interest of the heart. This reduces the signal-to-noise ratio and decreases, therefore, the image quality.